DE 10 2010 039 916 A1, which is incorporated by reference, describes a linear unit having a sensor device for capturing a rotor position of an electric motor, wherein the sensor device is configured as a contactlessly operating sensor arrangement which consists of a position encoder arranged on the longitudinal axis of the linear unit and of a non-movable position sensor element. In a known manner, the position encoder used is a magnet, and the position sensor element used is a magnetic field sensor.
The accuracy when positioning or commutating the rotor is limited by an occurring magnetic angular error at the magnetic field sensor, with respect to a preferred magnetic field direction. For modern motor vehicle systems, it is necessary, owing to increasing safety and comfort requirements with at the same time lower available space requirements, to exploit the potential efficiency of the electric motor, such as the maximally generated torque thereof, in an, improved manner. In addition, it is possible for further, possibly adjoining sensors, for example of a motor vehicle braking system, to be influenced significantly by occurring magnetic stray fields. As a result, safety-critical situations can be brought about and/or the comfort of vehicle occupants can be negatively affected. Known measures for dampening these stray fields with respect to further functional assemblies in the immediate vicinity are in particular ferromagnetic shielding plates which are located annularly around the magnets. When using a shielding plate, the magnet must under certain circumstances be dimensioned such that it is greater and/or thicker for properties of the sensor arrangement that stay the same. The shielding of magnetic stray fields thus leads to an increased space requirement and additional manufacturing costs.